Respiratory mask having a magnetically supported cushion

ABSTRACT

A patient interface face contact ( 14 ) element comprises a surface for contacting the face of a patient, and a connection face for coupling the patient interface face contact element to a support ( 15 ) using a magnetic coupling ( 30 ). The support is also provided as well as the complete patient interface. Headgear strap clips can also be retained magnetically.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims the priority benefit under 35 U.S.C. $371of international patent application no. PCT/IB2013/058712, filed Sep.20, 2013, which claims the priority benefit under 35 U.S.C. § 119(e) ofU.S. Provisional Application No. 61/703,974, filed on Sep. 21, 2012, thecontents of which are herein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to patient interfaces for transporting agas to and/or from an airway of a user.

BACKGROUND OF THE INVENTION

There are numerous situations where it is necessary or desirable todeliver a flow of breathing gas non-invasively to the airway of apatient, i.e. without inserting a tube into the airway of the patient orsurgically inserting a tracheal tube in their oesophagus. For example,it is known to ventilate a patient using a technique known asnon-invasive ventilation. It is also known to deliver continuouspositive airway pressure (CPAP) or variable airway pressure, whichvaries with the patient's respiratory cycle, to treat a medicaldisorder, such as sleep apnoea syndrome, in particular, obstructivesleep apnoea (OSA).

Non-invasive ventilation and pressure support therapies involve theplacement of a patient interface device including a mask component onthe face of a patient. The mask component may be, without limitation, anasal mask that covers the patient's nose, a nasal pillow/cushion havingnasal prongs that are received within the patient's nostrils, anasal/oral mask that covers the nose and mouth, or a full face mask thatcovers the patient's face. The patient interface device interfacesbetween the ventilator or pressure support device and the airway of thepatient, so that a flow of breathing gas can be delivered from thepressure/flow generating device to the airway of the patient.

Such devices are typically maintained on the face of a patient byheadgear having one or more straps adapted to fit over/around thepatient's head.

FIG. 1 shows a typical system to provide respiratory therapy to apatient. This is termed a “patient interface assembly”.

The assembly 2 includes a pressure generating device 4, a deliveryconduit 16 coupled to an elbow connector 18, and a patient interface 10.The pressure generating device 4 is structured to generate a flow ofbreathing gas and may include, without limitation, ventilators, constantpressure support devices (such as a continuous positive airway pressuredevice, or CPAP device), variable pressure devices, and auto-titrationpressure support devices.

Delivery conduit 16 communicates the flow of breathing gas from pressuregenerating device 4 to patient interface 10 through the elbow connector18. The delivery conduit 16, elbow connector 18 and patient interface 10are often collectively referred to as a patient circuit.

The patient interface 10 includes a mask 12, which in the exemplaryembodiment is a nasal and oral mask covering the nose and mouth.However, any type of mask, such as a nasal-only mask, a nasalpillow/cushion or a full face mask, which facilitates the delivery ofthe flow of breathing gas to the airway of a patient, may be used asmask 12. The mask 12 includes a cushion 14 coupled to a shell 15. Thecushion 14 is made of a soft, flexible material, such as, withoutlimitation, silicone, an appropriately soft thermoplastic elastomer, aclosed cell foam, or any combination of such materials. An opening inshell 15, to which elbow connector 18 is coupled, allows the flow ofbreathing gas from pressure generating device 4 to be communicated to aninterior space defined by the shell 15 and cushion 14, and then to theairway of a patient.

The assembly 2 also includes a headgear component 19, which in theillustrated embodiment is a two-point headgear. Headgear component 19includes a first and a second strap 20, each of which is structured tobe positioned on the side of the face of the patient above the patient'sear.

Headgear component 18 further includes a first and a second maskattachment element 22 to couple the end of one of the straps 20 to therespective side of the mask 12.

It is well known to include a forehead support to spread the requiredforces over a larger area. In this way, an additional cushion support onthe forehead balances the forces put by the mask around the nose or noseand mouth. This can be used to address a problem that the headgear forcevectors necessary to achieve a robust and stable seal against the faceof the patient can cut a straight line near the corners of a patient'seyes, which can be uncomfortable and distracting.

The seal that encloses the face or part of the face needs to bereplaceable, as frequent use induces wear and tear. A problem is that onone hand the fit of the replacement part with the mask shell 15 has tobe relatively loose, so as to enable an easy exchange. On the otherhand, however, the replacement part should fit to the mask shell tightlyas the two parts have to provide an airtight seal with each other.

Typically, silicon parts are used which have to be propped into placewith much dexterity. This can be difficult for a user to achieve.

SUMMARY OF THE INVENTION

According to the invention, there is provided a patient interface facecontact element and a patient interface support as claimed in theindependent claims.

In one aspect, the invention provides a patient interface face contactelement comprising a surface for contacting the face of a patient, and aconnection face for coupling the patient interface face contact elementto a support, wherein the contact element comprises a magnetic couplingarrangement associated with the connection face.

In another aspect, the invention provides a patient interface supportcomprising a coupling surface for coupling to a patient interface facecontact element, wherein the support comprises a magnetic couplingarrangement associated with the coupling surface.

The invention provides a fixation method for a patient interface facecontact element, which is the replaceable part of the patient interface.The interface face contact element can be a mask seal or a mask supportcushion, and these are frequently replaced due to wear and tear. Theinvention provides an arrangement which allows the replaceable parts tobe easily removable as well as providing a secure and airtight fit.

The magnetic coupling arrangement can comprise magnets which areinserted into retaining pockets or moulded into the structure. Themagnetic coupling arrangement of the face contact element can insteadcomprise a magnet arrangement to be applied against a back of theconnection face.

In one arrangement, the support comprises magnetic elements and the facecontact element comprises ferromagnetic regions for interfacing with themagnetic elements. In another arrangement, the face contact elementcomprises magnetic elements and the support comprises ferromagneticregions for interfacing with the magnetic elements. In anotherarrangement, the face contact element and the support each comprisemagnetic elements with opposite poles facing each other.

The invention also provides a patient interface for communicating a gasto the nose or the nose and mouth of a patient, comprising a support anda face contact element, wherein the face contact element and/or thesupport are in accordance with the invention.

The most basic version of the patient interface simply has the supportand face contact element magnetically coupled together. However, analternative embodiment has at least one headgear strap clip, wherein theclip is adapted to be retained magnetically by the magnetic couplingarrangement of the support and/or the face contact element.

In this way, a magnetic coupling of three components is provided; theclip, the support and the face contact element. The use of a releasableheadgear strap enables the patient interface to be fitted more easily.

The face contact element, the support and the clip can be stacked, andthe magnetic coupling arrangement then comprises at least one stack of amagnet element or elements and a ferromagnetic element or elements, withthe face contact element, the support and the clip each having arespective one of the elements. In this way, the magnetic couplingarrangement comprises one or more attachment points, at which the threecomponents are magnetically coupled together. For this purpose, themiddle component (which is the support) can have a magnet and the othercomponents can have ferromagnetic elements. However, any otherconfiguration is possible, with one, two or three magnets, and withnone, one or two ferromagnetic elements.

The patient interface then can include a headgear strap arrangement forcoupling to the headgear strap clip or clips.

The face contact element, the support and the clip can each comprisenon-planar physical alignment features. These can be used to resistdecoupling of the magnetic fixing resulting from the forces expected innormal use.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the invention will now be described in detail with referenceto the accompanying drawings, in which:

FIG. 1 shows a known patient interface;

FIG. 2 shows a first example of patient interface of the invention;

FIG. 3 shows different ways to configure the magnetic coupling in thepatient interface of FIG. 2;

FIG. 4 shows a second example of patient interface of the invention, inexploded view as well as in assembled view; and

FIG. 5 shows the magnetic coupling arrangement used in the patientinterface of FIG. 4 in more detail, in detached and attachedconfigurations.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention provides a patient interface face contact elementcomprising a surface for contacting the face of a patient, and aconnection face for coupling the patient interface face contact elementto a support using a magnetic coupling. The invention also provides apatient interface support comprising a coupling surface for coupling toa patient interface face contact element using a magnetic coupling.Headgear strap clips can also be retained magnetically.

A first embodiment is shown schematically in FIG. 2, in which the samereference numbers are used as in FIG. 1.

The patient interface comprises the mask shell 15 and the cushion 14.The mask shell 15 defines a plane substantially parallel to the face ofthe user. This is a coupling surface 28 the shell. One side of the shell15 away from the user's face is fitted with a supply of air fromdelivery tube 16, and the other side facing the user's face is coupledby the coupling surface 28 to the cushion 14 that fits over the noseand/or mouth of the user.

The cushion 14 includes a contact surface that is designed to sealagainst the user's face, and an opposing connection face 29 where itcouples to the coupling surface 28 of the mask shell 15.

The mask shell 15 is connected to the cushion 14 with a set of magneticfittings, comprising first magnetic elements 30 of the cushion 14 andsecond magnetic elements 32 of the shell 15. This allows the seal andcushion 14 to be easily removed and replaced even by an untrained user.

Various designs for the magnetic coupling are possible. For example, themagnetic coupling can also provide a self-alignment function to make theconnection more straightforward.

FIG. 3 shows different ways to integrate the magnets into the structureof the shell and cushion.

In FIG. 3A, the cushion 14 is a silicon seal part whereas the shell 15is a rigid plastics part. The magnets 30 for the cushion 14 are pushedinto respective pockets of the silicon cushion, and the magnets 32 forthe shell are pushed into the respective pockets of the shell.

In FIG. 3B, the magnets 30,32 are moulded into the silicon cushion andinto the mask shell.

In FIG. 3C, the magnets 30 for the cushion 14 are provided as a separatearrangement which is placed over the cushion after bringing the shell 15and cushion 14 together. The magnetic arrangement 30 can comprise a setof discrete magnets or a single ring which incorporates separatemagnets. This can then be applied against a back 34 of the connectionface 29 to clamp the connection face 29 against the coupling surface 28of the mask shell 15.

Thus, in these examples the magnets 32 of the shell and the magnets 30of the cushion 14 can injection moulded or inserted into pockets. Themagnets can instead be fixed to the mask shell and cushion using movableor flexible coupling elements.

In the examples of FIG. 3A to 3C, the replaceable part is the flexiblecushion part, which is typically silicone. However, the replaceable partcan include a rigid connection part to which the cushion is permanentlyattached.

The coupling between the replaceable part and the shell 15 can theninclude indexing features so that the coupling can only be made with thecorrect relative positioning, at which the magnetic coupling is mosteffective.

FIG. 3D shows an example in which the cushion 14 has a flexible part 14a and a rigid part 14 b, and the magnets 30 are provided in the rigidpart 14 b. Indexing features can ensure the correct relative positioningin a simple manner, for example with corresponding projections andrecesses, as schematically shown as 36.

The magnets themselves can also perform an indexing function, byproviding suitable orientation and/or shaping of the magnets.

The magnetic coupling can comprise magnets on one side and ferromagneticmaterial on the other side, or else magnets on both sides, with oppositepoles. Thus, only one of the two elements (shell and cushion) needs tohave magnets. Since the shell and cushion are otherwise non-metal (e.g.plastics and silicone), ferromagnetic materials can be used for magneticattraction to function in the same way as having opposing magnets.

Additional seal fittings may be used to improve the quality of theairtight seal between the cushion and the mask shell. For example acompressible seal can be provided on one or both of the shell andcushion so that the magnetic attraction force is used both to retain theparts together but also to actively compress a seal between the parts.An additional sealing component can be provided for placing around themagnetic coupling. However, any additional components should be easy foruser the since otherwise the object of providing the magnetic couplingis defeated.

This embodiment of the invention can be embodied as a replacementcushion alone, which is supplied separately to the rest of the patientinterface assembly, or it can be embodied as a mask shell part, or ascomplete a patient interface (i.e. a mask with shell and cushion), or asa full system.

This embodiment of the invention relates to the interface between themask shell and the cushion. For this reason, other components have notbeen shown in FIG. 2, such as the headgear, gas supply, or a foreheadsupport if desired. It will be appreciated that all of these knowncomponents and all of their known variations can be applied to thearrangement of the invention.

The invention can be applied to a nasal mask, an oral mask, a nasal/oralmask or a full face mask. The magnetic coupling can be applied to anypart that contacts the user's face and is therefore prone to wear andtear and therefore should be replaceable. In the examples above,permanent magnets are used to form the magnetic coupling. Electromagnetscould also be used. By reversing the electromagnet drive current in onecomponent, an inverse magnetic coupling can be created to assist thedecoupling operation. Thus, electromagnets can be used to provide thecoupling force but also to assist decoupling.

In the examples shown, the magnets face each other, so that the plane ofthe magnetic contact faces are perpendicular to the intended directionof application and removal of the magnetic coupling. Instead, themagnets can be arranged so that the coupling and/or decoupling isaccompanied by a sliding of the two magnets relative to each other. Thiscan provide an arrangement which is easier to separate. In this case,the magnetic faces are no longer perpendicular to the couplingdirection, but they are at an angle to the coupling direction. Themagnetic coupling can be pivotable between an orientation in which themagnetic faces are perpendicular to the coupling direction (for thecoupled configuration) and one in which they are angled to the couplingdirection, to facilitate removal. Thus, for component removal, themagnetic coupling can be rotated so that the decoupling can be based onsliding the magnets apart rather than pulling them apart.

The material of the seal can be used to create a hinge structure forthis purpose. This hinge is then manually moved during componentremoval.

As outlined above, this embodiment of the invention enables replacementof component parts, in particular the seal part against the user's face.It may be preferred that the part to be replaced does not contain themagnet, so that the magnet can be re-used. This is for example the casewith the design of FIG. 3C, but other designs which provide the magnetof the replaceable part as a non-integrated component are also possible.

The embodiment described above provides magnetic coupling of the maskcushion 14 to the shell 15.

In some known designs, the mask attachment element 22 (see FIG. 1) isdetachable from the shell 15 to enable easier fitting of the patientinterface 10. Removable headgear clips are known for this purpose. Forexample, these headgear clips can be snapped on using a talon clip andpost. For example, there may be two attachment elements 22 on each sideof the shell 15 (instead of the one shown in FIG. 1) with one on eachside being detachable to avoid having to pull straps all the way overthe head. A strap over the top of the head can be fixed to the shell,whereas a strap to go around the back of the head can be detachable.

The magnetic design described above can be extended so that a individualmagnetic coupling points provide an attachment location for both themask cushion (as described above) and also for a detachable headgearstrap. In this way, a multifunction embedded magnet system is provided,which can improve the assembly of both headgear mask clips, and thecushion.

In the same way as for the example above, the self-guiding feature of apair of magnets or else a magnet and a ferrous metal mating featureeases the assembly process for the user.

FIG. 4 shows a second example of patient interface of the inventionprovide magnetic clips, with an exploded view in FIG. 4A and anassembled view in FIG. 4B. The same components are given the samereference numbers as in FIGS. 1 to 3.

As shown in the example of FIG. 4A, the mask shell 15 is provided withthe magnets 30. They are used as attachments to both sides of the maskshell 15. To the inside of the mask shell, the cushion 14 a is removablyattached, and to the outside of the mask shell the mask attachmentelements 22 (in the form of clips) are attached. The headgear straps(shown in FIG. 1 but not shown in FIG. 4A or FIG. 4B) attach to theseclips 22.

In the example of FIG. 4A and FIG. 4B, the cushion 14 a is attached to arigid part 14 b (as already shown in FIG. 3D) in the form of a hub, andthe hub 14 b and cushion 14 a are together a disposable part of thepatient interface assembly.

The clips 22 are each provided with a magnet (or multiple magnets), or aferrous metal portion 42 which attaches over a corresponding magnet 30of the shell 15. Similarly, the hub 14 b has magnets, or ferrous metalportions 44 which attach beneath the magnets 30 of the shell 15.

Thus, a set of magnets, such as rare earth magnets, is embedded into theshell 15 near each headgear clip 22. The headgear clips have a matingfeature with the shell, centered on the magnet, and the hub 14 b alsohas a mating feature centred on the magnet. This allows the hub 14 b tobe self-guided on the shell, and the clips 22 to be self guided on theshell independently.

The three coupled parts need at least one magnet, and the other partsneed to be ferrous. However two or three magnets can be used at eachcoupling. Any combination of magnet and ferrous contact will suffice,but preferably with each contact including at least one magnet. The mostefficient implementation has a single magnet in the middle of the threelayer stack as shown, but there can be two or three magnets in the threelayer stack.

Thus, a preferred implementation has a magnet embedded into the shell 15and steel discs in the hub 14 b and the clips 22. If multiple magnetsare instead used, the polarity of the magnets must of course be alignedduring manufacturing.

Each of the components can use an overmolding process to place themagnet or steel inside the respective component, or else a press fitsecondary process can be used. The preferred type of magnet is an NdFeBmagnet, due to the low cost and high pull strength.

FIG. 5 shows the preferred magnetic coupling arrangement used in thepatient interface of FIG. 4 in more detail, in detached configuration inFIG. 5A and in attached configuration in FIG. 5B.

FIG. 5A shows that the shell 15 has an interlocking (non-planar) shape,rather than a flat planar profile. It has a projection one one side anda recess on the other. The projection faces the cushion in the exampleshown, and the hub 14 b has a corresponding recess. The recess of theshell faces the clip 22, which has a corresponding projection. Whenassembled as shown in FIG. 5B, these alignment features resistseparation of the magnets. For example the cushion force acts in adirection shown by arrow 50 whereas the headgear straps apply a forcecomponent in the direction shown by arrow 52. The alignment featuresreduce the effect of this force on separating the magnetic coupling.

In the example shown, the interconnection between the shell 15 and theclip 22 also includes an interlocking feature. The clip 22 has aprojection 16 and the shell 15 has a recess 17, thereby defining amale-female interlock. The magnet holds the clip 22 to the shell 15 andthe mechanical interlock allows the clip to stay in place when theheadgear is tightened and a shear force occurs. Of course, themechanical interlock can be swapped around.

Of course, any arrangement of projections and recesses can be used.

This embodiment improves the assembly and disassembly of both the clipsand cushion. Small rare earth magnets (e.g. a disc of diameter 1 cm andthickness 3 mm) generate pull forces of up to 45N and are relativelyinexpensive.

The magnets have been described above only for providing physicalcoupling of the mask shell and mask cushion, or for physically couplingthe strap arrangement. The magnetic coupling elements can also be usedas a means to convey electricity or electric signals from one componentto another, for example for reading out sensor signals.

The magnetic coupling does not have to define only a single possibleconnection position, and movable positions are also possible. For theexample with magnetic coupling of the strap arrangement for example, thestrap positions can be fixed, but the length of the straps can beadjusted. The straps can be fixed for example between two magneticelements at any position, or a number of magnetic elements in the strapcan provide for a number of pre-determined positions.

The magnets are preferably reusable and not disposable. For example,when the seal cushion is disposed of, the magnets should be re-used.This is clearly possible for the magnet arrangements of FIGS. 3A and 3D.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. The word “comprising” or “including”does not exclude the presence of elements or steps other than thoselisted in a claim. The word “a” or “an” preceding an element does notexclude the presence of a plurality of such elements. The mere fact thatcertain elements are recited in mutually different dependent claims doesnot indicate that these elements cannot be used in combination. Althoughthe invention has been described in detail for the purpose ofillustration based on what is currently considered to be the mostpractical and preferred embodiments, it is to be understood that suchdetail is solely for that purpose and that the invention is not limitedto the disclosed embodiments, but, on the contrary, is intended to covermodifications and equivalent arrangements that are within the scope ofthe appended claims. For example, it is to be understood that thepresent invention contemplates that, to the extent possible, one or morefeatures of any embodiment can be combined with one or more features ofany other embodiment.

The invention claimed is:
 1. A patient interface for communicating a gasto the nose or the nose and mouth of a patient, the patient interfacecomprising: a cushion comprising: a surface for contacting the face of apatient, a connection face disposed facing an opposite direction thanthe surface, and a first magnetic coupling arrangement associated withthe connection face; and a mask shell comprising: a coupling surface,and a second magnetic coupling arrangement associated with the couplingsurface, wherein the cushion is coupled to the mask shell via magneticattraction between the first magnetic coupling arrangement and thesecond magnetic coupling arrangement, wherein the first magneticcoupling arrangement comprises a magnet arrangement which is provided asa separate arrangement from the connection face which is placed over thecushion after the shell and cushion is brought together.
 2. The patientinterface as claimed in claim 1, wherein the first magnetic couplingarrangement comprises a magnet arrangement to be applied against a backof the connection face.
 3. The patient interface as claimed in claim 1,wherein the mask shell comprises a gas delivering coupling structured tobe coupled to a delivery conduit providing the gas for supply to thepatient.
 4. The patient interface as claimed in claim 1, wherein: thesecond magnetic coupling arrangement comprises magnetic elements and thefirst magnetic coupling arrangement comprises ferromagnetic regions forinterfacing with the magnetic elements; or the first magnetic couplingarrangement comprises magnetic elements and the second magnetic couplingarrangement comprises ferromagnetic regions for interfacing with themagnetic elements; or the first magnetic coupling arrangement and thesecond magnetic coupling arrangement each comprise magnetic elements. 5.The patient interface as claimed in claim 1, further comprising at leastone headgear strap clip, wherein the clip comprises a third magneticcoupling arrangement adapted to be retained magnetically by at least oneof the first magnetic coupling arrangement and/or the second magneticcoupling arrangement.
 6. The patient interface as claimed in claim 5,wherein the cushion, the mask shell and the clip are stacked, and eachof the first magnetic coupling arrangement, the second magnetic couplingarrangement, and the third magnetic coupling arrangement comprises: amagnet element or elements or a ferromagnetic element or elements. 7.The patient interface as claimed in claim 5, further comprising aheadgear strap arrangement for coupling to the headgear strap clip orclips.
 8. The patient interface as claimed in claim 5, wherein thecushion, the mask shell and the clip each comprise non-planar physicalalignment features.
 9. The patient interface as claimed in claim 1,wherein the arrangement comprises a set of discrete magnets.
 10. Thepatient interface as claimed in claim 1, where the arrangement comprisesa ring having a number of magnets disposed therein.